KANSAS CITY — When Amy Crump took over as director of the Marshall Public Library in central Missouri two years ago, she decided to build up the library’s offerings for young adults by buying the literary world’s hot new thing — graphic novels.

The novels, using the pictures and dialogue balloons of comic books to tell sometimes sophisticated stories in book form, are one of the fastest-growing sectors of the publishing industry, selling $250 million last year, according to market research firm ICv2 Publishing. But they’re also leading to challenges to libraries from some parents, who complain that the books with adult content could be read by children attracted to the comic book-like drawings.

“The bulk of our graphic novels are for young adults and they’re very popular,” Crump said, estimating the library’s collection has gone from only a handful to around 75.

The Daniel Boone Regional Library, the system serving Boone and Callaway counties, has 781 graphic novels, representing less than two percent of its total holdings, said Doyne McKenzie, the system’s collection development manager.

Among Crump’s acquisitions in Marshall were “Blankets” by Craig Thompson and “Fun Home: A Family Tragicomic” by Alison Bechdel, two semi-autobiographical accounts of the respective authors’ turbulent childhoods that include ruminations on a strict religious upbringing and homosexuality.

Those two novels touched off what Crump said was the first challenge of library materials in the library’s 16-year history. Parents complained that the books, which include pictures of a naked couple, could be read by children, attracted by the comic book-like drawings.

“My concern does not lie with the content of the novels, rather my concern is with the illustrations and their availability to children and the community,” said Marshall resident Louise Mills during a recent public hearing reported in The Marshall Democrat-News. “Does this community want our public library to continue to use tax dollars to purchase pornography?”

The library board has since removed the two books from circulation while it develops a policy governing how it collects materials in the future, a policy that would determine the novels’ eventual fates.

The DBRL, on the other hand, does not plan to remove books, McKenzie said.

“We are firm believers of freedom of access and totally support parents who want to monitor what their children are reading,” McKenzie said. “We’re not going to remove something because children might get it. There are some people who want to read them, and those people should have access.”

McKenzie said the DBRL has not had any complaints from patrons about any graphic novels.

Sales of graphic novels have more than tripled from $75 million in 2001. Milton Griepp, chief executive of ICv2, which tracks pop culture retail, estimated libraries add 5 to 10 percent to those retail sales.

“The last two or three years’ growth has been pretty rapid in libraries, and that’s because graphic novels have started to be respected as legitimate literature,” Griepp said.

“Maus,” a Holocaust memoir by Art Spiegelman, won a Pulitzer Prize in 1992, while this year Gene Luen Yang’s “American Born Chinese” became the first graphic novel to be nominated for the National Book Award. Spiegelman’s book was one of the first graphic novels the DBRL acquired, McKenzie said.

But some people who may have never heard of graphic novels are alarmed to see cartoon characters doing and saying very adult things.

“I think there’s still a perception in the general public that comics are just for kids, which isn’t true and hasn’t been true for years,” Griepp said.

The Chicago-based American Library Association said it knows of at least 14 graphic novel challenges in U.S. libraries over the past two to three years. Among the titles were “Watchmen” by Alan Moore, which was challenged in Florida and Virginia as unsuitable for younger readers; “Akira, Volume 2” by Katsuhiro Otomo, challenged in Texas for offensive language; and “New X-Men Imperial” by Grant Morrison, challenged in Maryland for nudity, offensive language and violence.

Even “Maus” and its sequel, “Maus II,” were challenged last year in Oregon as anti-ethnic and unsuitable for younger readers.

Sometimes the book challenges are successful. In April, county officials in Victorville, Calif., removed from their library “Manga: 60 Years of Japanese Comics,” because the book included nudity and sexuality.

“Some people find graphical depictions of things more offensive than text,” said Carrie Gardner, a spokeswoman for the ALA’s Committee for Intellectual Freedom and a professor at The Catholic University of America in Washington, D.C.

The issue has become prevalent enough that the ALA, the National Coalition Against Censorship and the Comic Book Legal Defense Fund earlier this year put out a set of recommendations for librarians who are looking to begin their own graphic novel collections but wanting to avoid controversy.

The recommendations largely explain how to deal with challenges but also suggest shelving graphic novels in their own section or keeping those aimed at adults separate from those for youngsters.

At DBRL libraries, McKenzie said most graphic novels are shelved in the non-fiction adult section and some in the young adult section

“Graphic novels are extremely popular to all ages since we started to have a display in the library in 2001,” McKenzie said.

Gardner said discussions around graphic novels are similar to what happened when libraries began carrying videotapes and providing access to the Internet.

“Librarians are trained to conduct reference interviews and guide patrons to the resources most appropriate for them,” Gardner said. “They should be making those decisions.”